2008 S ICHUAN E ARTHQUAKE, C HINA H2CG04: Geology for Civil Engineers PRESENTATION By Ka Hang CHAN Samuel KOROMA 1Sichuan Earthquake, China

W HERE IS S ICHUAN P ROVINCE ? 2Sichuan Earthquake, China

D ISASTER D ETAIL 12 May, 2008: 14:28 CST 8.0 Ritcher Scale (revised) Epicentre: Wenchuan Aftershocks: 42,719 Death Toll: 69,181 Missing: 18,498 Injured: 374,147 Homeless: 10m 3Sichuan Earthquake, China

T ECTONICS - 1 Plate collision Indian Plate pushing Eurasian Plate northward (40mm/yr) – Large scale structural deformation – Thinning crust of Qinghai-Tibet Plateau – Eastward extrude Qinghai-Tibet Plateau – East-northward movement – Overrides the Sichuan basin (4 mm/yr) 4Sichuan Earthquake, China

T ECTONICS - 2 Longmenshan thrust formation – Sichuan basin stronger crust against Tibetan crustal material – Caused compressive stress & thrust fault Sudden dislocation – Hence, VIOLENT EARTHQUAKE 5Sichuan Earthquake, China

R UPTURED F AULT L INES Max vertical slippage – 60km NE of epicentre – 12m Rupture originated 10 km below surface Rupture closer to the surface = Stronger shaking Sichuan Earthquake, China6

C AUSES OF D AMAGE TO B UILDINGS - 1 Strong seismic intensity – Up to XI (Mercalli) – China’s quake-resistance standard: VII – Energy = x5600 Atomic Bomb (1945) – Did the Seismic code underestimate the earthquake strength? 7Sichuan Earthquake, China Source: U.S. Geological Survey

C AUSES OF D AMAGE TO B UILDINGS - 2 Geological condition under houses – Heavy sedimentation – Highest land rise: 6m Sichuan Earthquake, China8

C AUSES OF D AMAGE TO B UILDINGS - 3 “The Shoddy Tofu Buildings” 8 schools (7,000 classrooms) – Other nearby buildings little damaged Builders cutting corners – Replaced steel rods with thin iron wires for concrete reinforcement – Use inferior grade cement (or no cement at all!) – Use less bricks Sichuan Earthquake, China9

Thanks for Watching! 10Sichuan Earthquake, China SI (four)CHUAN (river)